Crankshaft grinder



Sept. 6, 1938. u. G. WILLIS v CRANKSHAFT GRINDER Filed July is, 1956 fi/yams fli/Zz INVENTOR ATTORNEY Patented Sept. 6, 1938 UNITED STATES PATENT OFFICE My invention relates to improvements in tools for truing crankshafts, that is in truing the shaft by cutting out the unevenly worn surfaces or Where the shaft has been scored.

Crankshaft bearings, particularly in interna combustion engines, become substantially 'oval in crosssection from wear, and it has been the practice heretofore in truing up the worn bearings, to remove the crankshaft from the engine fl and true the shaft in a lathe. I am aware that other devices similar to my invention have been used in truing crankshafts, but so far as I am aware none of these machines are built and constructed along the principle of my device, which 15 is simple in construction and will perform the service desired very economically.

The principal object of my invention is the provision of a tool of the nature referred to which will enable the crankshaft to be reground or trued 20 up without removal of the shaft from the engine and to fit the tool to the shaft in such a way as to feel out the surfaces that need cutting and truing at the bearings.

Another object of my invention is to provide 25 a tool of this nature wherein the cutting elements and guide elements are so arranged that neither the guide elements nor the cutter elements are directly opposite one another-this for the purpose of preventing wobbling when 30 there is a high spot on one side of the shaft and a low spot on the other side. My invention also prevents chattering of the tool because of the novel arrangement of the cutters and guides and prevents the cutting elements from 35 digging into the shaft which sometimes occurs.

The above and other objects of my invention will become apparent from a perusal of the following detailed description, taken in connection with the accompanying drawing, and in the 40 drawing:

Figure 1 is a side elevational view of my tool, the view being partly broken away and shown in section, the dotted lines indicating the open position of the tool;

45 Figure 2 is a sectional detail view had on the line 2--2 of Figure 1;

Figure 3 is an enlarged detail view, partly broken away, of the preferred form of cutter and guide holder by itself;

5 Figure 4 is an enlarged cross-sectional view taken on the line 4-4, Figure 1, showing one of the cutter holders in operable position.

Continuing the description in detail, like parts bearing like reference characters, the tool is pref- 55 erably constructed of bronze or other suitable metal and as assembled is circular in form and the two arcuate parts I and 2 thus provide an opening 3 whentogetherr The sections I and 2 are provided with projecting ears 4 for hingedly ;pin 5. Likewise projecting ears 6 and 1 having a bolt and nut assembly 8 are provided for sercurelyfastening the parts or sections in operable position.

Instead of constructing my tool in two equal 10 sections or halves, it will be observed that the section I is of a greater semi-annular extent than that of the section 2, and the section 2 is of lesser semi-annular extent, thus completing the annular formation. In this form of construction it is only necessary to loosen the nut 8 and the tool can be easily removed from the crankshaft. Each of the sections l and 2 are bored or drilled at spaced intervals thus forming the recesses 9' for the insertion of an implement, rod or the like, to rotate the tool in the cutting operation.

The means for performing the cutting operation is provided by the cutting elements l0, spaced around the inner periphery of the sections l and 2 and projecting forwardly into the opening 3. These cutting elements are mounted in a cutter holder having a headportion H with an enlarged portion I2 and a threaded shank l3. Spaced bores are made in the sections l and 2 as at A to admit these cutter holders as will be clear from Figure 1. The head II is channeled as at M to receive the cutter elements l0 and each head is provided with screw holes l5 for screws I6. These screws are for the purpose of adjusting the cutter elements to the correct cutting position, according to the condition of the shaft to be ground.

To move the cutter holders forwardly or backwardly from the shaft or inwardly or outwardly in the sections I and 2 there is provided on each threaded shank l3 the force nut as shown more clearly in Figure 4. The exposed end 18 of this force nut is knurled as shown to enable force to be more easily applied manually and its inner end I! is provided with an annular groove [9. A pin 20, traversing the sections l and 2, seats in the groove and thus holds the nut from backward or forward longitudinal movement, but permits the shank and head of the cutter holder to move inwardly or outwardly as the case might require, when the knurled portion I8 of the nut is turned.

Between each cutter element l0 there are disposed two guide elements lil each guide element being supported on a holder exactly like the cutguide element 10*. The holder may be used for carrying and supporting either a cutter element or a guide element.

To prevent the holders for guide and cutter elements from rotating when the knurled end l8 of the force nut is turned, I provide keys 22, shown in position in Figure 2. These keys are arc-shaped so as to lie within the annular channel l in the inner periphery of the two sections l and 2. Each key is held in position by a screw 23. In Figure 3 I show a longitudinal groove I2 in the enlarged portion l2 of the cutter holder and the ends of these keys seat in these grooves and lie between each holder, as will be clearly seen in Figure 1. Thus the holders are prevented from turning but they are permitted to slide inwardly and outwardly when the force nut is turned-the pins 20 holding the force nut from moving inwardly or outwardly.

In the operation of the tool, the cutter elements and guide elements may be set to a predetermined size and the tool then placed on the shaft, or placed on the shaft and the cutters and guides adjusted and the tool rotated by means of an implement placed in the recesses 9.

While I have shown and described a practical working embodiment of my invention, it is to be understood that I do not limit my invention to the precise construction here shown, as modifications may be made without departing from the principle of my invention and within the scope of the appended claim.

What I claim as new is:

A tool of the character described, comprising arcuate sections hingedly connected together and providing a central opening in the tool when the parts are closed, means for holding and releasing said arcuate sections to and from operable position on a shaft, each arcuate section being provided with radially disposed recesses for manual rotation of the tool by an implement, each section having radial bores in spaced relation, a plurality of cutter and guide holders disposed in said bores and the said holders being provided with cutter and guide elements, a groove in the inner periphery of the said arcuate sections and arc-shaped key elements being positioned in the said groove between each of the holder elements, means for holding the key elements in position, and a vertical groove in each side of each of the holder elements for seating the said key elements so as to prevent rotation of said holders when each of the said holders is being independently moved to and from the said opening.

ULYSSES G. WILLIS. 

